Performance analysis of Dual Mixed Refrigerant System in Cryogenic Distillation Column as carbon capture at Acid Gas Removal Unit

In natural gas processing, the presence of acid gas by-products such as hydrogen sulfide (H 2 S) and carbon dioxide (CO 2 ) poses significant environmental concerns, necessitating effective mitigation strategies. This study investigates the reduction efficiency of acid gases through cryogenic distillation integrated with a Dual Mixed Refrigerant (DMR) cooling process, using a simulation-based approach. The simulation models the performance of various combinations of natural gas (NG) and amine solutions (MDEA) in the Acid Gas Removal Unit, designated as Process 1 (NG A & MDEA A), Process 2 (NG A & MDEA B), Process 3 (NG B & MDEA A), and Process 4 (NG B & MDEA B). The findings reveal that Process 3 achieves the most effective separation of CO 2 and H 2 S, with maximum molar fraction separations of 28.06% and 67.15%, respectively. Moreover, H 2 S removal reaches its peak efficiency in Process 3, with a reduction rate of 92.91%, indicating the potential of the cryogenic distillation column system when combined with MDEA. Despite these promising results, CO 2 removal remains limited, with the highest reduction of only 40.94% also observed in Process 3, suggesting the need for further optimization. Additionally, the DMR system successfully reduces the temperature and pressure of natural gas to -163°C and 110 kPa, respectively. Process 3 exhibits a notable molar fraction decrease of 0.88%, underscoring its superior performance among the configurations studied.